The photograph shows a vacuum pump part. It consists of a highly filled thermoset and was made in a special mold. The sharp edge of the drilled bore demonstrates the ability of the material to be machined, due to its toughened composition.
Polymeric materials, which for instance are designed for use in oilfree vaccum aggregates, must operate at continuous service temperatures around 250 °C without loss of their mechanical and thermal properties. Most usual matrix materials, e.g. epoxy resins, unsaturated polyesters, or phenolic resins, have usual operating temperatures below 250 °C. Other high temperature materials (e. g. Vespel® by DuPont) or are by far too expensive.
Another essential requirement is a low coefficient of thermal expansion (CTE) to match the CTE of the surrounding metal parts to avoid thermal stresses and resulting material failure. The objectives of this project are to find composite materials for high temperatures with a low CTE around 10 to 14 ppm/K and to test their suitability for the production of bulk thermal setting parts. Several steps are approached: 1. The selection of promising high temperature matrix materials. 2. The production of mixtures with different fillers. 3. The production of sample geometries in a simple form to test mechanical and thermal properties of the composite and 4. Scale-up of promising mixtures and fabrication of larger parts for first tests in vaccum pumps.